Vibrator devices



p 1961 E. TORCHEUX ETAL 2,999,919

VIBRATOR DEVICES Filed May 8, 1959 2 Sheets-Sheet l FIG. I PRIOR ART FIG.2 PRIOR ART FIG.3 PRIOR ART p 1961 E. TORCHEUX ETAL 2,999,919

VIBRAIOR DEVICES 2 Sheets-Sheet 2 Filed May 8, 1959 United States Patent Morocco Filed May 8, 1959, Ser. No. 811,833 Claims priority, application France May 10, 1958 2 Claims.

The problem frequently arises of deriving alternating currents of comparatively low frequencies, for example 100 to 1000 c./s., from direct current sources.

To this end, vibrator devices are provided which generally comprise two stationary armatures and a member upon which vibratory motion is impressed, causing it to engage periodically and alternately the two stationary armatures, the vibration frequency being the frequency of the alternating current derived.

Devices of this type show, however, many disadvantages. The rapid movement of the vibratory member may, on the long run, cause deformation thereof, the contacts thus becoming poor. Further, each time the vibratory element strikes one of the stationary armatures, it tends to rebound therefrom, which prevents the estab lishment of a clean contact.

It is an object of the invention to provide a vibrator having none of these drawbacks.

A vibrator according to the invention essentially comprises a mobile element on which an alternating movement is impressed and two stationary armatures, having respective contact surfaces forming with the direction of movement of the mobile element an angle which is substantially equal to the angle of friction between the materials from which said mobile element and said stationary armatures are made.

According to a preferred embodiment of the invention, the mobile element is guided during its motion in such a manner that the surfaces engaging each other should be always the same.

The invention will be best understood from the following description and appended drawings wherein:

FIG. 1 is a cross-sectional, diagrammatical view of a vibrator of a conventional type;

FIG. 2 is the connection diagram of the vibrator of FIG. 1;

FIG. 3 illustrates, as a function of time, the voltage provided by the device of FIG. 1;

FIG. 4 is a cross-sectional view of a vibrator device according to the invention.

FIG. 5 shows, as a function of time, the voltage provided by the vibrator of FIG. 4;

FIG. 6 shows a more elaborate embodiment of the device according to the invention.

FIGS. 7, 8 and 9 show details of the device of FIG. 6.

Referring to FIG. 1, a vibrator is shown having two fixed armatures 1 and 2 with plane, parallel contact surfaces. Armatures 1 and 2 are connected to the two terminals of a D.C. source 4, one of these terminals being connected to a point A as shown in FIG. 2.

The ball-shaped mobile member is grounded at C and means are provided (not shown) for impressing on ball 3 an oscillatory movement, thus causing it to impinge alternately on armatures 1 and 2. To this end, the assembly may be, for example, placed on a vibrating table.

The voltage collected between terminals A and C has theorically, when plotted against time, the shape illustrated by the dotted line in FIG. 3, i.e. it forms a sequence of regular crenels, the voltage abruptly jumping from zero to the maximum value, i.e. to the voltage of source 4, then falling just as abruptly again to zero. However, the

. vibrator does not behave that way in actual practice.

"ice

Ball 3, upon striking the armature, is subjected to a reaction force which is directed along the normal to the contact surface and is proportional to v v being its velocity, and accordingly rebounds from the armature several times. This results in the electric contacts not being immediately established. The potential between points A and C undergoes several fluctuations resulting in noise, which may be detrimental in certain applications. The actual voltage between points A and C is shown in full line in FIG. 2. The assembly thus behaves as a condenser which is alternately charged and discharged and voltage V across points A and B appears to result from a damped oscillation.

The vibrator according to the invention which is illustrated in FIG. 4 also comprises two stationary armatures 21 and 22. The contact surfaces are preferably goldplated and form an angle therebetween. The mobile member 23 is shaped as a portion of a cylinder which has been out along a plane parallel to its axis and which has a hollow central portion. This cylinder portion rests on a metallized base 5 which is grounded.

Element 23 is subjected to a reciprocating movement relative to stationary members in the directions represented by the arrows in FIG. 4 and forming an angle 1 with the two contact surfaces.

The value of angle 1 is selected to be substantially equal to the friction angle between element 23 and elements 21 and 22.

The operation of the device is as follows:

Element 23, upon engaging one of the armatures 21 and 22, tends to rebound in a direction making an angle 1 with the normal common to the two contacting surfaces. The reaction force is therefore directed substantially along a line perpendicular to the direction of the reciprocating motion of element 23 and will accordingly not affect this motion. No rebounding of element 23 will therefore actually take place. In fact, it is difficult to determine the value of f with an absolute precision and this theoretical condition is therefore not obtained. However, the rebounding, if not entirely eliminated, is minimized to a substantial degree.

FIG. 5 shows the resulting alternating voltage as a function of: time. It will be noted that the crenels have almost perfectly steep edges and that the eifect of rebounding, which is shown at L, is eliminated for all practical purposes with the consequent elimination of noise.

FIG. 6 shows in cross-section a more elaborate embodiment of a vibrator according up to the invention.

It comprises a grounded base member 12 which is shown in plane View in FIG. 9, a guiding member 11 which is shown in plane view in FIG. 8 and an upper plate 10, a top view of which may be seen in FIG. 7. As may be seen in FIG. 6, elements 12, 11 and 10 are superimposed on each other and are of generally circular contour in which registering notches 24 and 25 are provided for keeping the three elements assembled together by any suitable means.

Base 12 is plane with the exception of a small portion thereof forming an inclined plane 14, which is preferably silvered for providing a convenient grounding connection. The remainder of the upper surface of base 12, which is made of a shock resistant ceramic material, is preferable covered with a gold deposit.

Guiding member 11 is also ceramic. It comprises a slot 13 adapted for guiding movable member 23, when the assembly shown in FIG. 6 is placed on a vibrating table.

Upper plate 10 is seen in a bottom view in FIG. 6. It comprises a ceramic plate 26 on the lower surface of which are affixed two members 27 and 28, which may also be ceramic and whose terminal portions are shaped as elements 21 and 22 of FIG. 4. Contact surfaces 31 and 32 are gold plated and silver covered notches 15 and 16 are provided in the lower surface of elements 27 and 28 for connection thereof to a DC. source.

The arrangement shown, in addition to the advantages already mentioned prevents any displacement of element 23 in any direction other than the desired one. This is a considerable advantage, since the contact between the moving element 23 and surface 31 and 32 always occurs at the same place. After a certain time of operation, a certain wear of the contacting surfaces takes of necessity place, resulting in the appearance of bumps and hollows thereon, but such bumps and hollows are of a complementary character. Therefore, as long as the gold coating is not worn out, the quality of the contact is in no way impaired.

The invention is of course not limited to the embodiment described and shown which is given merely by Way of example.

What is claimed is:

1. A vibrator device comprising in combination: two stationary armatures having respective planar contact surfaces; a hollow cylinder portion bounded by a plane parallel to its axis; a conductive body having a planar surface, said hollow portion being arranged for effecting over said planar surface a reciprocating motion of a predetermined direction for periodically and alternately engaging said planar contact surfaces, said contact surfaces form- 4 ing with said direction an angle substantially equal to the angle of friction between said cylinder portion and said armatures; and means for guiding said motion of said cylinder portion.

2. A vibrator device comprising in combination: two stationary armatures, having respective planar contact surfaces; a hollow cylinder portion, bounded by a plane par-.

References Cited in the file of this patent UNITED STATES PATENTS 923,962 Fessender June 8, 1909 2,286,611 Farmer June 16, 1942 2,359,136 McConnell et al.. Sept. 26, 1944 2,485,170 Roetter Oct. 18, 1949 2,497,306 Landmeier Feb. 14, 1950 2,540,854 Woestemeyer Feb. 6, 1951 2,541,398 Wood Feb. 13, 1951 

